Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S938584AbcKLATX (ORCPT ); Fri, 11 Nov 2016 19:19:23 -0500 Received: from muru.com ([72.249.23.125]:59502 "EHLO muru.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935171AbcKLATW (ORCPT ); Fri, 11 Nov 2016 19:19:22 -0500 Date: Fri, 11 Nov 2016 16:19:17 -0800 From: Tony Lindgren To: "Rafael J. Wysocki" Cc: Brian Norris , Dmitry Torokhov , "Rafael J . Wysocki" , Pavel Machek , Len Brown , Greg Kroah-Hartman , lkml , Brian Norris , "linux-pm@vger.kernel.org" Subject: Re: [PATCH] PM / wakeirq: report wakeup events in dedicated wake-IRQs Message-ID: <20161112001917.GN7138@atomide.com> References: <1478801227-65527-1-git-send-email-briannorris@chromium.org> <20161110184910.GA135921@google.com> <20161111163147.GC7138@atomide.com> <20161111222911.GL7138@atomide.com> <20161111223234.GM7138@atomide.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2932 Lines: 59 * Rafael J. Wysocki [161111 15:35]: > On Fri, Nov 11, 2016 at 11:32 PM, Tony Lindgren wrote: > > * Tony Lindgren [161111 14:29]: > >> * Rafael J. Wysocki [161111 13:33]: > >> > On Fri, Nov 11, 2016 at 5:31 PM, Tony Lindgren wrote: > >> > > * Rafael J. Wysocki [161110 16:06]: > >> > >> On Thu, Nov 10, 2016 at 7:49 PM, Brian Norris wrote: > >> > >> > On Thu, Nov 10, 2016 at 10:13:55AM -0800, Dmitry Torokhov wrote: > >> > >> >> On Thu, Nov 10, 2016 at 10:07 AM, Brian Norris wrote: > >> > >> >> > It's important that user space can figure out what device woke the > >> > >> >> > system from suspend -- e.g., for debugging, or for implementing > >> > >> >> > conditional wake behavior. Dedicated wakeup IRQs don't currently do > >> > >> >> > that. > >> > >> >> > > >> > >> >> > Let's report the event (pm_wakeup_event()) and also allow drivers to > >> > >> >> > synchronize with these events in their resume path (hence, disable_irq() > >> > >> >> > instead of disable_irq_nosync()). > >> > >> >> > >> > >> >> Hmm, dev_pm_disable_wake_irq() is called from > >> > >> >> rpm_suspend()/rpm_resume() that take dev->power.lock spinlock and > >> > >> >> disable interrupts. Dropping _nosync() feels dangerous. > >> > >> > > >> > >> > Indeed. So how do you suggest we get sane wakeup reports? Every device > >> > >> > or bus that's going to use the dedicated wake APIs has to > >> > >> > synchronize_irq() [1] in their resume() routine? Seems like an odd > >> > >> > implementation detail to have to remember (and therefore most drivers > >> > >> > will get it wrong). > >> > >> > > >> > >> > Brian > >> > >> > > >> > >> > [1] Or maybe at least create a helper API that will extract the > >> > >> > dedicated wake IRQ number and do the synchronize_irq() for us, so > >> > >> > drivers don't have to stash this separately (or poke at > >> > >> > dev->power.wakeirq->irq) for no good reason. > >> > >> > >> > >> Well, in the first place, can anyone please refresh my memory on why > >> > >> it is necessary to call dev_pm_disable_wake_irq() under power.lock? > >> > > > >> > > I guess no other reason except we need to manage the wakeirq > >> > > for rpm_callback(). So we dev_pm_enable_wake_irq() before > >> > > rpm_callback() in rpm_suspend(), then disable on resume. > >> > > >> > But we drop the lock in rpm_callback(), so can't it be moved to where > >> > the callback is invoked? > >> > >> Then we're back to patching all the drivers again, no? > > > > Sorry I misunderstood, yeah that should work if rpm_callback() drops > > the lock. > > It still will not re-enable interrupts if the irq_safe flag is set. I > wonder if we really care about this case, though. We have at least 8250-omap and serial-omap using wakeirqs with irq_safe flag set. Regards, Tony